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Pelican Deaths, Dispersal at Chase Lake National Wildlife Refuge

Date Posted: July 13, 2005

The U.S. Fish and Wildlife Service is investigating high chick mortality and the departure of many of the American white pelicans at Chase Lake National Wildlife Refuge near Medina, North Dakota. 1. A July 8 inspection revealed about 300-500 live chicks remaining after a nesting period that had the potential to produce as many as 9,000. However, biologists believe the estimate of live chicks remaining is likely low because tall vegetation is hindering visibility. That same check showed about 2,000 adults remaining from a late May population estimated at 18,850. Samples have been collected and sent to the National Wildlife Health Center in Madison, Wis. to determine the cause of the chick mortality. Preliminary results could be available in a week. Following the disappearance of about 30,000 pelicans from the colony in late May and early June 2004, the Service and its partners, including the U.S. Geological Surveys Northern Prairie Wildlife Research Center and the ND Game and Fish Department, began intensive monitoring of the colony to learn more about the abandonment of nests, eggs and newly-hatched chicks. Scientists have yet to determine what caused the 2004 abandonment. Researchers on site last week noted that the remaining chicks are being cared for by the adults, which is a key difference from last year, when adults abandoned both nests and young. The Service and its partners took several steps in the spring of 2005 to minimize human disturbance. The Service restricted visitor access to the nesting areas to reduce the risk of disturbance during the sensitive nesting period. A barrier fence was constructed to exclude predators such as coyotes and foxes from the peninsula colony where abandonment was first observed last year. Additionally, cameras and human observers with binoculars and spotting scopes are being used to monitor the colony. Although we havent been able to come up with the reason for the 2004 abandonment, noted Service spokesperson Ken Torkelson, we hoped a return to normalcy at Chase Lake this year would have given us more time to study it. He added, Unfortunately, this years high chick mortality may complicate that investigation. It is still entirely possible that last years abandonment was a quirk of nature; one of those strange occurrences that never gets explained. The pelican colony at Chase Lake National Wildlife Refuge has been the largest in North America, peaking at 35,466 birds in 2000 after the population was as low as 50 pelicans in the early 1900s.

The pelican colony at Chase Lake National Wildlife Refuge has been the largest in North America, peaking at 35,466 birds in 2000 after the population was as low as 50 pelicans in the early 1900s.